This invention relates to an electrical load center or panel, and more particularly to such a panel which is adapted to be supplied with power from a primary power source and which also includes a power input from an auxiliary power source so as to supply power to the panel in the event of an outage or interruption in the supply of power from the primary power source.
An electrical load center or panel typically includes a main switch, in the form of a circuit breaker, that is interconnected with a primary power source such as utility power. The main switch or breaker is operable to control the supply of power to the electrical panel from the utility. In some electrical panels, the main breaker is center-mounted and includes a main breaker switch member or handle that is movable between an ON position and an OFF position. The panel also includes a series of connection areas which are adapted to mount a series of branch circuit breakers for distributing power from the electrical panel to the various loads within the building. The connection areas are oriented such that the switches of the branch circuit breakers are movable between ON and OFF positions in a direction parallel to the direction of movement of the main breaker switch member between its ON and OFF positions.
In order to ensure a constant supply of power to the loads interconnected with the branch circuit breakers, it is known to mount an auxiliary main breaker to certain of the connection areas of the electrical panel, and to interconnect the auxiliary main breaker with an auxiliary power supply such as a standby generator or the like. The auxiliary main breaker is typically mounted to the electrical panel adjacent the primary main breaker, and includes a switch member movable between ON and OFF positions in a direction parallel to that of the switch member of the primary main breaker, to control the supply of power to the electrical panel from the auxiliary power source. In this type of arrangement, it is important to ensure that the switch members of the primary and auxiliary main breakers cannot both be in the ON position at the same time, to prevent power from being simultaneously supplied to the electrical panel from both the primary and the auxiliary power sources. Various interlock arrangements have been developed to address this problem, and examples are illustrated in Flegel U.S. Pat. Nos. 5,761,027; 6,031,193; and 6,184,595, the disclosures of which are hereby incorporated by reference.
It is an object of the present invention to provide an interlock for a dual power source electrical panel which is effective to prevent the switch members of both the primary and auxiliary main breakers from being in the ON position at the same time, to ensure that the electrical panel is supplied with power from only a single power source at any one time. It is a further object of the invention to provide such an interlock which is adapted for use in an electrical panel in which the switch members of the primary and auxiliary main breakers are spaced apart from each other and are movable in parallel directions between their ON and OFF positions. It is a further object of the invention to provide such an interlock which can be relatively quickly and easily mounted to the electrical panel in the vicinity of both the primary and auxiliary main breakers. Yet another object of the invention is to provide such an interlock which is configured so as to prevent removal of the auxiliary main breaker from the panel, while enabling removal of the primary main breaker from the panel. A still further object of the invention is to provide such an interlock which can be configured so as not to interfere with the connection areas of the electrical panel so as to maximize the number of branch circuit breakers or other devices that can be mounted to the electrical panel. A still further object of the invention is to provide such an interlock which is intuitive in operation so as to provide ease of use by a user. Yet another object of the invention is to provide such an interlock which is relatively simple in its components and construction, yet which is capable of providing relatively quick and easy connection to the panel and a reliable and effective interlock mechanism for ensuring that the branch circuit breakers are not simultaneously supplied with power from two different power sources.
In accordance with the present invention, an electrical panel includes a first or primary switch, in the form of a circuit breaker having a movable switch member, that is interconnected with a primary source of power such as utility power. The electrical panel further includes a second or auxiliary switch, in the form of an auxiliary main breaker having a movable switch member, that is interconnected with a secondary power source such as a standby generator. The auxiliary breaker is mounted to the panel adjacent the primary breaker, such that a space is located between the auxiliary breaker and the main breaker. An interlock is interconnected with the electrical panel within the space between the primary and auxiliary breakers, and is operable to ensure that the switch member of the primary breaker cannot be moved to its ON position when the auxiliary breaker switch member is in its ON position, and vice versa, to prevent the panel from being supplied with power from both the primary and auxiliary power sources at the same time.
The interlock includes a support arrangement connected to the electrical panel, and an interlock member that is movably mounted to the support arrangement for movement between first and second interlock positions. In its first interlock position, the interlock member is positioned in line with the auxiliary breaker switch member in its OFF position, so as to prevent movement to its ON position, and is positioned relative to the primary breaker switch member so as to enable movement between its ON and OFF positions. In its second interlock position, the interlock member is positioned in line with the primary breaker switch member in its OFF position, so as to prevent movement to its ON position, and is positioned relative to the auxiliary breaker switch member so as to enable movement between its ON and OFF positions.
In one form, the auxiliary breaker is located vertically below the primary breaker, and the interlock member is configured so as to rest on the auxiliary breaker switch member in its ON position, to maintain the interlock member in its second interlock position. In this manner, when the auxiliary breaker switch member is moved from its ON position to its OFF position, support for the interlock member is removed and the interlock member is moved from its second interlock position to its first interlock position. In the event the electrical panel is mounted in a vertical orientation with the auxiliary breaker below the primary breaker, the interlock member is biased by gravity toward its first interlock position so as to move toward its first interlock position when the auxiliary switch member is moved to its OFF position. This prevents subsequent return of the auxiliary breaker switch member to its ON position until the primary breaker switch member is moved to its OFF position, which allows the interlock member to be placed in its second interlock position from its first interlock position. The electrical panel may also be in a vertical orientation with the primary breaker below the auxiliary breaker, such that the interlock member is subjected to a gravity bias toward its second interlock position.
The interlock support arrangement includes a support post connected to and extending from the electrical panel, and a support base secured to the support post. The interlock member is slidably interconnected with the support base for movement between its first and second interlock positions. The support base may include a pair of spaced apart slide members between which the interlock member is received. Movement of the interlock member between its first and second interlock positions may be controlled by means of a guide surface associated with the support base which engages a guide edge defined by the interlock member, in combination with a slot formed in the interlock member which receives a stud associated with the support base for controlling movement of the interlock member. Engagement of the stud with the ends of the slot is operable to define the range of motion of the interlock member between its first and second interlock positions.
The support base is preferably configured so as to engage the auxiliary breaker and maintain the auxiliary breaker in engagement with the electrical panel. The support arrangement is further configured so as not to interfere with the primary breaker when the primary breaker is engaged with the electrical panel, so as to enable removal of the primary breaker from the electrical panel if desired. The auxiliary breaker preferably includes an outwardly facing surface, and the support arrangement is configured so as to overlie a portion of the outwardly facing surface to prevent removal of the auxiliary breaker. The support arrangement further includes an edge located adjacent a side surface of the primary breaker. The support arrangement does not overlap any outwardly facing surfaces of the primary breaker, so that the primary breaker can be moved outwardly for removal from the electrical panel.
The electrical panel may further include a power meter arrangement for measuring power supplied to either or both of the primary and auxiliary breakers. The power meter arrangement may be in the form of a meter mounting bracket secured to a back wall defined by a housing associated with the electrical panel, and one or more power meters mounted to the meter mounting bracket. The meter mounting bracket is preferably located on an opposite side of the main breaker from the interlock, and the meter mounting bracket is configured so as to define an edge located adjacent an opposite side surface of the primary breaker, such that the meter mounting bracket also does not interfere with outward movement of the primary breaker relative to the panel, if desired.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.